How the Test is Performed

Blood sample

How to Prepare for the Test

You may need to stop taking some medicines before this test. Your health care provider will tell you which ones.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

This test is used to find the cause of too much bleeding (decreased blood clotting). Or, it may be ordered if a family member is known to have
hemophilia B
. The test may also be done to see how well treatment for hemophilia B is working.

Hemophilia B

Normal Results

A normal value is 50 to 200% of the laboratory control or reference value.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests.